1. Field of the Invention
The present disclosure relates to a liquid crystal display device, and more particularly, to a liquid crystal display (LCD) device for strengthening an adhesion between an upper ITO layer of color filter substrate and an electrostatic prevention means in a small-sized model having an in-plane switching (IPS) mode liquid crystal panel to prevent a ground fault.
2. Discussion of the Related Art
In today's information society, the importance of display devices is more emphasized as a visual information transmission medium, but their requirements such as low power consumption, thin profile, light weight, high picture quality should be satisfied in order to occupy the principal position in the future.
Display devices can be largely divided into an emissive type display capable of spontaneously emitting light such as cathode ray tube (CRT), electroluminescent (EL), light emitting diode (LED), vacuum fluorescent display (VFD), field emission display (FED), plasma display panel (PDP), and the like, and a non-emissive type display incapable of spontaneously emitting light such as liquid crystal display device.
The liquid crystal display is a device for expressing images using optical anisotropy of liquid crystal molecules, and in recent years, it is spotlighted as a second-generation device along with a PDP display because its visibility is more excellent than CRT, and its average power consumption and heat dissipation is lower than that of CRT with the same screen size.
Since liquid crystals used in the liquid crystal display device are not a light-emitting material, which spontaneously emits light, but a light-receiving material, which modulates an amount of light to display an image on the screen, and therefore, it is required to have a separate light source, namely, a backlight assembly for irradiating light to the liquid crystal panel.
Hereinafter, the liquid crystal display device will be described in detail.
If not particularly mentioned, a portion in which a lamp is placed is referred to as a lower portion, and a portion in which a liquid crystal panel is placed is referred to as an upper portion in a finished liquid crystal display device.
A liquid crystal display device may include a liquid crystal panel in which liquid crystal molecules are injected between an array substrate and a color filter substrate to output an image, a backlight assembly provided on a rear surface of the liquid crystal panel to emit light over an entire surface of the liquid crystal panel, and a plurality of case elements for fixing the liquid crystal panel to the backlight assembly to combine them with each other.
The backlight assembly functions to make a plane wave having a uniform luminance from the lamp that is used as a light source, and the backlight assembly can be largely divided into an edge type and a direct type based on a position of the light source with regard to the display surface thereof.
FIG. 1 is a cross-sectional view schematically illustrating a related art liquid crystal display device.
As illustrated in the drawing, a liquid crystal panel 10 configured by adhering an array substrate on which a plurality of pixels are formed in a matrix form to a color filter substrate on which R, G, and B filters are formed in a matrix form, is laminated with a backlight assembly to be accommodated into a support main 60.
Here, though not specifically shown in the drawing, at a side edge of the liquid crystal panel 10, a gate printed circuit board (PCB) for applying drive signals is connected to a gate pad of the liquid crystal panel 10 by interposing a gate taped carrier package (TCP) through a flexible cable.
Similarly, at the other side edge of the liquid crystal panel 10, a data PCB for applying graphic signals is connected to a data pad of the liquid crystal panel 10 through a flexible cable, and a data TCP for applying signals to the liquid crystal panel 10 based on a predetermined scanning method is adhered to them.
Furthermore, an upper polarizer 5 and a lower polarizer 15 are adhered to the upper and lower portions of the liquid crystal panel 10 respectively.
In a lower portion of the liquid crystal panel 10 having the foregoing configuration, it is laminated a backlight assembly including a plurality of optical sheets 43, a lamp (not shown) for generating light to express an image, a light guide plate 44 for converting light generated from the lamp into a plane wave to output it toward the liquid crystal panel 10 in the upper portion thereof, and a reflection sheet 45 for reflecting light leaked from the light guide plate 44 to enhance optical efficiency.
Here, the backlight assembly and the liquid crystal panel 10 are inserted into a support main 60 in a laminated form to protect them from an external shock as well as providing an optical alignment therebetween.
Furthermore, a top case 50 and a bottom case 55 are fastened to the support main 60 in which the liquid crystal panel 10 and the backlight assembly are accommodated.
Here, the top case 50 and bottom case 55 performs a role of grounding the PCB connected to the liquid crystal panel 10 and also performs a role of protecting the liquid crystal panel 10 and the backlight assembly.
On the other hand, in a related art in-plane switching (IPS) mode liquid crystal display device 1 having the foregoing configuration, an upper ITO 11 for discharging static electricity generated on a color filter substrate is formed at an upper portion of the liquid crystal panel 10.
Furthermore, in case of using a support main 60 mold structure, the upper ITO 11 is grounded to the bottom case 55 using a ground tape 70, and at this time it may cause quality failure due to weak grounding because an adhesion area of the ground tape 70 is small. In addition, there may exist a possibility that adhesion failure is caused due to such a small ground area when adhering the ground tape 70 thereto.
At this time, in case of increasing a thickness of the bottom case 55 in the arrow direction in order to secure an adhesion area of the ground tape 70 as illustrated in the drawing, it may cause a problem that an overall thickness of the liquid crystal display device 1 is also increased. In particular, in small-sized models under 5-inch, an increase of the thickness in the liquid crystal display device 1 may not meet the user's requirement for slimming liquid crystal display devices.
On the other hand, in case of fastening a liquid crystal panel to a backlight assembly using a guide panel, the upper ITO is grounded toward the guide panel which is a press part, and there may be a failure problem that the ground tape is detached after adhering to an adhesion portion of the upper ITO of the color filter substrate.